The present invention generally relates to an improved electric field forming device used either as an ion generating unit in an electrophotographic copier or as an ozone gas generator. More particularly, the invention relates to an electric field forming device of the type wherein an RF high voltage is applied between a discharge electrode and an inductive electrode formed on opposite sides of a ceramic dielectric substrate.
The discharge electrode of an electric field forming unit of the type contemplated by the present invention is formed on a ceramic dielectric substrate by the screen printing of a paste of electroconductive powder. The nature of the screen printing technique is such that a discharge electrode having smooth edges or one having a good linearity cannot be obtained, and a surface having an unevenness of 40 microns or more is not infrequent. As a result, no uniform corona discharge is obtained along the periphery of the screen-printed discharge electrode, even if an RF high voltage is applied between that electrode and an inductive electrode.